JSON: Add support for echo option

The basic principle is to not return a JSON object freshly created from
netlink responses, but just update the existing user-provided one to
make sure callers get back exactly what they expect.

To achieve that, keep the parsed JSON object around in a global variable
('cur_root') and provide a custom callback to insert handles into it
from received netlink messages. The tricky bit here is updating rules
since unique identification is problematic. Therefore drop possibly
present handles from input and later assume updates are received in
order so the first rule not having a handle set is the right one.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/netlink.h b/include/netlink.h
index 5ff129ed..a8528d59 100644
--- a/include/netlink.h
+++ b/include/netlink.h
@@ -55,6 +55,12 @@ struct netlink_ctx {
 extern struct nftnl_expr *alloc_nft_expr(const char *name);
 extern void alloc_setelem_cache(const struct expr *set, struct nftnl_set *nls);
 
+extern struct nftnl_table *netlink_table_alloc(const struct nlmsghdr *nlh);
+extern struct nftnl_chain *netlink_chain_alloc(const struct nlmsghdr *nlh);
+extern struct nftnl_set *netlink_set_alloc(const struct nlmsghdr *nlh);
+extern struct nftnl_obj *netlink_obj_alloc(const struct nlmsghdr *nlh);
+extern struct nftnl_rule *netlink_rule_alloc(const struct nlmsghdr *nlh);
+
 struct nft_data_linearize {
 	uint32_t	len;
 	uint32_t	value[4];